The flower color plays a crucial role in the interaction between plants and their pollinators. The main pigment of yellow P. nudicaule flowers are nudicaulins, a group of unique indole alkaloids.

Their structure suggested formation from a chalcone-related moiety and an indole-type precursor. This biosynthesis is still obscure. Previous retrobiosynthetic studies with 13CO2 demonstrated that the indole part is derived from the indole/ tryptophan pathway and polyphenolic part from the flavonoid biosynthesis. The results from intensive feeding experiments with 13C-labelled precursors revealed that pelargonidin glucosides and indole are the final precursors of the nudicaulin formation.

On going studies aim to gain a in-depth insight into the biosynthesis network of the nudicaulin production, its regulation and the precursor sources using state-of-the-art methods.